The present invention relates generally to an x-ray tube assembly, and, more particularly to an x-ray tube target assembly with improved balancing characteristics.
X-ray tubes are well known and widely utilized in a variety of medical imaging fields, medical therapy fields, and material testing and analysis industries. They are commonly comprised of both an anode assembly and a cathode assembly. X-rays are produced when electrons are released in a vacuum with the tube, accelerated and then abruptly stopped. The electrons are released from a heated filament. A high voltage between the anode and the cathode accelerates the electrons and causes them to impinge on the anode. The anode is also referred to as the target since the electrons impact the anode at the focal spot.
In order to dissipate the heat generated at the focal spot, X-ray tubes often incorporate a rotating anode structure. The anode in these arrangements commonly comprises a rotating disc so that the electron beam constantly strikes a different point on the target surface. In order to handle the considerably heat generated by even transient focal spots, present x-ray tube target assemblies are commonly rotated at high rotational speeds. As these speeds increase it becomes more and more critical to have the rotating target assembly properly balanced around its rotational axis. Improper balance can result in unacceptable operational stresses on the target assembly and surrounding structures. Unbalanced assemblies can further introduce chatter and may impart noise into the x-ray tube assembly. In addition, proper balance can effect image quality and bearing wear.
Current techniques for insuring proper balance in the x-ray tube target assembly commonly are comprised for material finishing techniques performed on the finished x-ray target assembly. These techniques use simple material removal operations. Although simple, the use of this material processing technique can lead to unacceptable results. Since existing techniques are performed on finished products, and error in material removal can result in a scrap product. This in turn adds to overall cost increases and delays in manufacturing. Additionally, the removal of material on a finished product can results in the production of particles that may not be all removed after balancing. If all of the resultant particles are not removed they may result in a reduction in high voltage stability of the x-ray tube assembly. Finally, the use of material removal as a basis for balancing the target assembly can result in excessive material removal, which in turn can result in stress problems for the x-ray target assembly during operation. There is, therefore, considerable room for improvement over material processing balancing techniques.
It would, however, be highly desirable to have an x-ray target assembly that could be easily balanced without requiring material removal from the finished product. Similarly, it would be highly desirable to have an x-ray target assembly with balancing features that could be nondestructively modified to balance the x-ray target.